Stability of Quad-Helix/Crib Therapy in Dentoskeletal Open Bite: a Long-Term Controlled Study

ORIGINAL ARTICLE

Stability of quad-helix/crib therapy in dentoskeletal open bite: A long-term controlled study

Manuela Mucedero,a Lorenzo Franchi,b Veronica Giuntini,c Andrea Vangelisti,c James A. McNamara, Jr,d and Paola Cozzae Rome and Florence, Italy, and Ann Arbor, Mich

Introduction: The purpose of this study was to evaluate the long-term stability of quad-helix/crib treatment in subjects with dentoskeletal open bite. Methods: Twenty-eight subjects (11 boys, 17 girls; mean age, 8.2 6 1.3 years) were treated consecutively with quad-helix/crib appliances. The patients were reevaluated at the end of active treatment with the quad-helix/crib (mean age, 9.7 6 1.6 years) and at least 5 years after the completion of treatment (mean age, 14.6 6 1.9 years). A control group of 20 untreated subjects with the same dentoskeletal disharmony was used for the statistical comparison (Mann-Whitney U test). Results: In the long term, the quad-helix/crib group showed a signiﬁcant reduction in the ANB angle (1.3), a downward rotation of the palatal plane (1.8), a greater increase in overbite (2.1 mm), and a decrease in overjet (1.5 mm) when compared with the controls. Conclusions: In the long term, the use of the quad-helix/crib appliance led to successful outcomes in about 93% of the patients considered. Correction of dentoskeletal open bite was associated with a clinically signiﬁcant downward rotation of the palatal plane. (Am J Orthod Dentofacial Orthop 2013;143:695-703)

nterior open bite is characterized by a localized skeletal relationships are significant risk factors for the Aabsence of occlusion between the incisal edges establishment of an anterior open bite.6,7 Subjects with of the maxillary and mandibular teeth when dentoskeletal open bite and sucking habits often have the remaining teeth are in occlusion.1,2 This concomitant transverse discrepancies.8 Many authors malocclusion occurs because of interferences during have emphasized that a skeletal open bite should be normal dental eruption and alveolar development. treated early in the mixed dentition to allow for normal Several factors are involved in the etiology of anterior development of the anterior dentoalveolar region.9-11 open bite.3-6 Thumb sucking and increased vertical Various treatment approaches can be found in the literature with regard to early treatment of anterior open bite.12-18 The elimination of persisting sucking aResearch fellow, Department of Orthodontics, University of Rome “Tor Vergata,” habits and the control of the vertical dimension must Rome, Italy. be therapeutic objectives. The correction of maxillary bAssistant professor, Department of Orthodontics, University of Florence, Flor- ence, Italy; Thomas M. Graber Visiting Scholar, Department of Orthodontics constriction is an additional target for treatment in 19 and Pediatric Dentistry, School of Dentistry, University of Michigan, Ann Arbor. patients with open bite. cResearch associate, Department of Orthodontics, Universita degli Studi di The use of a palatal crib has been proposed as an Firenze, Firenze, Italy. dThomas M. and Doris Graber Endowed Professor of Dentistry, Department of excellent treatment option, because it prevents thumb 3,20-23 Orthodontics and Pediatric Dentistry, School of Dentistry; research professor, or pacifier sucking, as well as tongue thrust. Center for Human Growth and Development, University of Michigan, Ann Arbor. According to Haryett et al,22 the palatal crib is effective eProfessor and chair, Department of Orthodontics, University of Rome “Tor Vergata,” Rome, Italy. for the elimination of a thumb-sucking habit in 85% to The authors report no commercial, proprietary, or financial interest in the 90% of subjects. Studies reporting the success of early products or companies described in this article. treatment in subjects with anterior open bite when Reprint requests to: Lorenzo Franchi, Dipartimento di Odontostomatologia, Universita degli Studi di Firenze, Via del Ponte di Mezzo, 46-48, 50127 Firenze, compared with a well-matched control group, however, Italy; e-mail, lorenzo.franchi@unifi.it. are scarce in the literature. Only 2 studies have Submitted, September 2012; revised and accepted, January 2013. incorporated untreated controls with the same type of 0889-5406/$36.00 fi Copyright Ó 2013 by the American Association of Orthodontists. dentoskeletal disharmony, but they were con ned 24,25 http://dx.doi.org/10.1016/j.ajodo.2013.01.010 to short-term observations. The authors of both 695 696 Mucedero et al

studies analyzed the effects of a removable palatal crib observation at least 5 years after the completion of associated with a vertical-pull chincup; this treatment treatment (T3); and treatment with the Q-H/C appliance protocol did not produce significant changes in the for at least 12 months.17 skeletal maxillary and mandibular components. The All subjects were at a prepubertal stage of skeletal results of both studies showed that the effects of therapy maturity according to the cervical vertebral maturation primarily were dentoalveolar. method (CS 1 or CS 2) at T1.30 The overall observation A proposed treatment protocol aimed to eliminate period was 6.4 6 1.4 years, which included a follow- the thumb-sucking habit and to correct both the up period of at least 5 years during which the Q-H/C anterior open bite and the maxillary transverse patients were treated with fixed appliances. No active deficiency in growing high-angle subjects is a quad-helix biomechanics or vertical elastics to extrude the incisors (Q-H) appliance with the addition of a palatal crib were applied during fixed appliance therapy. No (Q-H/C).17,25 When compared with the effects of intraoral Class II elastics were used. a removable appliance (open-bite bionator or All subjects had reached postpubertal skeletal removable palatal crib), the Q-H/C appliance was maturity at T3 (CS 4-6). The stages of cervical vertebral shown to be significantly more effective in the maturation were determined by a calibrated examiner improvement of overbite in the short term.26,27 The (L.F.) trained in this method. All patients were in the treatment and posttreatment effects of a Q-H/C permanent dentition at T3. appliance showed a clinical effectiveness in correcting A control group of 20 subjects (10 girls, 10 boys) with the dental open bite of 85% of the patients after anterior open bite was retrieved from the archives of the a follow-up of 2 years.28 This favorable result was University of Michigan Growth Study and the Denver associated with clinically significant improvement in Child Growth Study. The control group matched the the maxillomandibular vertical skeletal relationships. Q-H/C group for negative overbite at T1, chronologic No data, however, are available in the literature about age, and skeletal maturation at the various time periods the outcomes of the Q-H/C appliance reevaluated at and for the duration of intervals. a follow-up of at least 5 years. The mean ages at the 3 time periods in both the The purpose of this study, therefore, was to evaluate Q-H/C and control groups and the duration of the long-term stability of Q-H/C treatment in subjects either treatment or observation intervals are given in with thumb-sucking habits and anterior dentoskeletal Table I. open bite. Both active treatment and posttreatment The Q-H appliance used in this study was made of effects were analyzed in consecutively treated patients, 0.036-in stainless steel wire soldered to bands on the and these results were compared with the growth second deciduous molars or the first permanent molars changes in an untreated control group with the same (Fig).25 The lingual arms of the appliance extended dentoskeletal disharmony during a follow-up period of mesially to the deciduous canines or to the permanent at least 5 years. incisors. The anterior helices were brought as far forward on the palate as possible. Spurs to prevent thumb MATERIAL AND METHODS sucking were formed from 3 segments of 0.036-in The Q-H/C sample comprised 28 subjects (17 girls, 11 stainless steel wire soldered to the anterior bridge of boys) who were treated consecutively at the Department the Q-H. The wire segments were inclined lingually to of Orthodontics at the University of Rome “Tor Vergata” prevent impingement on the sublingual mucosa.25 or in a private orthodontic practice in Rome. Lateral Activation of the Q-H was equivalent to the buccolingual cephalograms of treated patients were analyzed width of 1 molar. The appliance was reactivated once or regardless of treatment results. Each patient had the twice during treatment to achieve overcorrection of the following features: thumb-sucking habit before transverse relationships. treatment; negative overbite; constricted maxillary The T1, T2, and T3 cephalograms were hand traced arch as consequence of thumb sucking; full eruption by 1 investigator (V.G.) and then verified for landmark of first permanent molars and permanent incisors location by a second investigator (L.F.). Any disagree- (to prevent the “pseudo-open bite” due to undererupted ments were resolved by retracing the landmark or permanent incisors)29; no permanent teeth extracted structure to the satisfaction of both observers. before or during treatment; 3 consecutive lateral Cephalometric software (Viewbox, version 3.0; dHAL cephalograms of good quality with adequate landmark Software, Kifissia, Greece) was used for a customized visualization and minimal or no rotation of the head, digitization regimen that contained 21 variables taken before treatment (T1), at the end of the active (11 linear, 10 angular). The magnification factor of the treatment with the Q-H/C (T2), and at a follow-up cephalograms was standardized at 8%.

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Changes in the 2 groups were compared by Table I. Demographics of the groups nonparametric tests, since normal distribution Q-H/C group (n 5 28) Control group (n 5 20) (Kolmogorov-Smirnov test) or equality of variances Chronologic (Levene test) could not be assessed for all variables. In age (y) Mean SD Mean SD T1 8.2 1.3 8.1 0.4 general, parametric tests are more powerful than T2 9.7 1.6 9.8 0.4 nonparametric statistics. However, the assumptions T3 14.6 1.9 14.5 0.7 required for parametric tests are particularly important T1-T2 1.5 0.4 1.7 0.4 when sample sizes are small, with small usually thought T2-T3 4.9 1.3 4.7 0.6 to be fewer than 30 in each group; if the assumptions T3-T1 6.4 1.4 6.4 0.7 cannot be verified, then nonparametric methods should be used.35 Before making the comparisons of the longitudinal changes, significant differences between the craniofacial starting forms at T1 were assessed with the Mann-Whitney U test between the Q-H/C and control groups. To assess the differences between the Q-H/C and control groups with regard to T1 to T2, T2 to T3, and overall T1 to T3 changes, Mann-Whitney U tests (P \0.05; P \0.01; and P \0.001) were used. Chi-square tests with the Yates correction were performed to compare the prevalence rates of correction of anterior open bite in the 2 groups at T2 and T3. The Fig. Intraoral view of the Q-H/C in place. correction of anterior open bite at the dentoalveolar level was considered to be obtained when the overbite Statistical analysis measurement was equal to or greater than 0 mm. Descriptive statistics (mean differences and standard The data were analyzed with statistical software (SPSS deviations) were calculated for all cephalometric 21.0 and SigmaStat version 3.5; Systat Software, Point measurements at T1, and for the changes from T1 to Richmond, Calif). Statistical significance was tested at T2, T2 to T3, and T1 to T3 in both groups. P \0.05. The power of the study was 0.91 for an alpha The homogeneity between the Q-H/C and control level of 0.05 and an effect size equal to 136 for the groups for skeletal maturity at each observation time clinically relevant variable palatal plane to mandibular and mean duration of observation intervals allowed for plane angle, as derived from a previous study.28 comparisons without annualizing the data. Matching To test the reliability of the measurements, 20 lateral between treated and control subjects was tested also cephalograms randomly selected from various subjects in by means of propensity score analysis.31 This matching the study were retraced and remeasured by the same ex- protocol in observational studies allows researchers to aminer (V.G.) after a 1-month interval.37 No systematic mimic randomization by creating a sample of subjects error was found with the Wilcoxon signed rank test. who did not receive treatment comparable on all Random errors were estimated with Dahlberg's observed covariates with the sample of subjects who formula.38 The errors for linear measurements ranged received treatment.32,33 The program “psmatching”33 from 0.1 mm for pogonion to nasion perpendicular, to (available at http://sourceforge.net/projects/psmspss/ 1.2 mm for condylion-gonion. The errors for angular files) was used to calculate propensity scores and to measurements ranged from 0.4 for ANB angle, to test matching between the treated and control samples 1.4 for interincisal angle. (SPSS version 21.0; IBM, Armonk, NY). Propensity scores were calculated for some clinically relevant covariates RESULTS (Wits, Frankfort horizontal to palatal plane, palatal plane Analysis of the starting forms (Table II) showed that the to mandibular plane, and overbite) whereas all other Q-H/C and the control groups had no statistically signifi- variables were entered as additional covariates. An cant differences in craniofacial characteristics at T1. The overall balance chi-square test developed by Hansen only exception was a significantly longer ramus length and Bowers34 was applied to test group matching. This (Co-Go) at T1 in the Q-H/C group. For the dentoskeletal test examines all covariates that were used to estimate features at T1, the vertical skeletal relationship was in- the propensity scores and all variables that were defined creased, and the sagittal intermaxillary relationship was as additional covariates. skeletal Class II in both groups. The overall matching

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Table II. Comparison of starting forms (T1)

Q-H/C group (n 5 28) Control group (n 5 20)

Cephalometric measurement Mean SD Mean SD Difference Significance Maxillary skeletal SNA () 82.1 2.9 80.7 3.2 1.4 NS Point A-nasion perp (mm) 2.4 2.7 1.1 3.0 1.3 NS Mandibular skeletal SNB () 76.8 3.2 75.4 2.0 1.4 NS Pg-nasion perp (mm) 5.5 6.6 8.5 4.0 3.0 NS Co-Gn (mm) 106.3 6.5 104.3 3.9 2.0 NS Maxillary/mandibular ANB () 5.3 2.4 5.4 2.0 0.1 NS Wits (mm) 1.6 2.7 1.5 2.6 0.1 NS Vertical skeletal FH-PP () 3.1 3.4 3.4 2.8 0.3 NS MPA () 28.5 4.2 27.9 4.4 0.6 NS PP-mandibular plane () 31.5 4.9 31.3 4.0 0.2 NS ANS-Me (mm) 65.1 5.7 64.9 4.1 0.2 NS Co-Go (mm) 49.3 3.3 47.2 3.5 2.1 * Gonial angle () 131.7 5.1 130.2 4.2 1.5 NS Interdental Overjet (mm) 2.8 2.9 3.6 1.8 0.8 NS Overbite (mm) 3.3 1.6 2.2 2.3 1.1 NS Interincisal angle () 122.0 9.7 125.7 11.0 3.7 NS Molar relationship (mm) 0.4 1.9 0.8 1.3 0.4 NS Maxillary dentoalveolar U1-Point A vert (mm) 4.4 2.3 3.8 1.8 0.6 NS U1-FH () 117.0 7.8 114.3 6.8 2.7 NS Mandibular dentoalveolar L1-Point A Pg (mm) 2.1 2.1 1.9 2.2 0.2 NS L1-MPA () 93.1 6.0 92.6 7.1 0.5 NS NS, Not significant; perp, perpendicular; Pg, pogonion; FH, Frankfort horizontal; PP, palatal plane; U1, maxillary central incisor; vert, vertical; L1, mandibular central incisor; NS, not significant. *P \0.05. between the treated and control groups was assessed fur- group. The comparison was statistically significant ther with propensity scores. The chi-square balance test (chi-square 5 5.58; P 5 0.018). was not statistically significant (chi-square 5 28.154; No significant differences in posttreatment changes P 5 0.081), thus indicating good overall balance (T2-T3) were found between the Q-H/C and control between the 2 groups. groups (Table IV). The statistical comparisons of the T1 to T2 changes The evaluation of the overall treatment changes from (Table III) showed no statistically significant differences T1 to T3 (Table V) showed significant differences in the between the Q-H/C and control samples for any sagittal skeletal relationships. The intermaxillary skeletal maxillary or mandibular skeletal measurements in the relationships showed a significant reduction in the ANB sagittal plane. For the vertical skeletal measurements, angle of 1.3 in the Q-H/C group compared with the the Q-H/C group exhibited greater downward rotation control group. Vertical skeletal variables maintained of the palatal plane than did the control group a significant improvement in the Q-H/C group vs the (1.9 mm). A significant effect of therapy was found for controls (Frankfort horizontal to palatal plane, 1.8; the dentoalveolar variables. The Q-H/C group showed palatal plane to mandibular plane, 2.2). Overbite a significantly greater increase in overbite (2.2 mm had a significantly greater increase in the Q-H/C group more than the control group) associated with 5.7 of (2.1 mm more than the control group), and a significant lingual tipping of the mandibular incisors relative to decrease was found for overjet in the Q-H/C group vs the the mandibular plane with respect to the controls. controls (1.5 mm). After active treatment (T2), the prevalence rates for At the follow-up observation (T3), 26 subjects (93%) correction of overbite were 86% (24 subjects) in the in the Q-H/C group showed a corrected overbite. This Q-H/C group and 50% (10 subjects) in the control prevalence rate was significantly greater than that in the

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Table III. Comparison of changes during treatment (T1-T2)

Q-H/C group (n 5 28) Control group (n 5 20)

Cephalometric measurement Mean SD Mean SD Difference Significance Maxillary skeletal SNA () 0.2 1.8 1.0 4.3 0.8 NS Point A-nasion perp (mm) 0.2 1.7 1.0 4.0 0.8 NS Mandibular skeletal SNB () 1.1 1.3 1.2 3.2 0.1 NS Pg-nasion perp (mm) 2.6 2.2 2.3 6.2 0.3 NS Co-Gn (mm) 4.1 3.3 4.3 1.9 0.2 NS Maxillary/mandibular ANB () 0.9 1.3 0.1 1.8 0.8 NS Wits (mm) 0.2 2.4 1.9 3.7 2.1 NS Vertical skeletal FH-PP () 1.7 3.6 0.2 2.5 1.9 * MPA () 0.6 3.3 0.5 3.6 0.1 NS PP-mandibular plane () 2.2 2.2 0.3 2.1 1.9 * ANS-Me (mm) 0.9 1.6 1.9 1.5 1.0 NS Co-Go (mm) 1.8 2.8 2.1 2.2 0.3 NS Gonial angle () 1.7 2.7 1.2 3.1 0.5 NS Interdental Overjet (mm) 0.3 2.2 1.0 1.3 0.1 NS Overbite (mm) 4.2 1.8 2.0 1.6 2.2 y Interincisal angle () 6.2 9.6 1.7 6.3 7.9 NS Molar relationship (mm) 0.5 1.8 0.1 1.8 0.4 NS Maxillary dentoalveolar U1-Point A vert (mm) 0.5 1.8 1.1 1.4 0.6 NS U1-FH () 0.3 6.1 1.2 5.6 0.9 NS Mandibular dentoalveolar L1-Point A Pg (mm) 0.8 1.9 0.5 1.2 1.3 NS L1-MPA () 3.7 5.8 2.0 2.8 5.7 y NS, Not significant; perp, perpendicular; Pg, pogonion; FH, Frankfort horizontal; PP, palatal plane; U1, maxillary central incisor; vert, vertical; L1, mandibular central incisor. *P \0.05; yP \0.01. control group (15 subjects, 70%; chi-square 5 2.90; P 5 the developmental period (early developmental 0.036). phases) that is known as the optimal time for rees- tablishing normal dentoskeletal relationships.7,20 DISCUSSION For the same ethical reasons, it would be The specific features of this study were the following. impossible to collect a contemporary control group of subjects with untreated anterior open 1. Patients were treated consecutively; they were bite with an observation in the long term. included in the study regardless of treatment outcome. A posttreatment observation (T2) was All subjects treated with the Q-H/C protocol ceased obtained at the end of the active treatment with the thumb-sucking habit, as was noted in a previous the Q-H/C, and a long-term appraisal (T3) was study.17 No patient resumed thumb-sucking habits available at least 5 years after treatment. during the posttreatment period. 2. The control sample consisted of subjects with The results of the T1 to T2 interval showed no untreated anterior open bite, and they matched statistically significant differences between the 2 groups the Q-H/C group as to type of dentoskeletal for the maxillary and mandibular skeletal components or malocclusion, age interval, skeletal maturation at the maxillomandibular relationships. Q-H/C therapy different time points, and sex distribution produced on average about 2.0 of downward rotation (Table I). Although historical control groups might of the palatal plane with respect to the controls. As have limitations,39 in our study the use of historical a result, intermaxillary divergence as measured by the controls was due to the lack of ethical rationale to angle between the palatal plane and the mandibular leave patients with anterior open bite untreated at plane exhibited a significant mean reduction of about

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Table IV. Comparison of changes after treatment (T2-T3)

Q-H/C group (n 5 28) Control group (n 5 20)

Cephalometric measurement Mean SD Mean SD Difference Signiﬁcance Maxillary skeletal SNA () 0.8 2.6 0.5 4.4 1.3 NS Point A-nasion perp (mm) 0.5 2.7 0.7 4.7 1.2 NS Mandibular skeletal SNB () 0.2 2.4 0.9 3.7 0.7 NS Pg-nasion perp (mm) 1.2 4.9 2.3 7.9 1.1 NS Co-Gn (mm) 10.1 6.4 11.5 3.2 1.4 NS Maxillary/mandibular ANB () 1.0 2.0 0.5 1.6 0.5 NS Wits (mm) 0.8 4.2 0.4 4.9 0.4 NS Vertical skeletal FH-PP () 0.6 3.5 0.5 1.9 0.1 NS MPA () 2.7 3.0 2.3 2.5 0.4 NS PP-mandibular plane () 2.1 2.7 1.8 2.9 0.3 NS ANS-Me (mm) 5.4 3.8 5.7 2.5 0.3 NS Co-Go (mm) 5.4 5.2 6.5 3.3 1.1 NS Gonial angle () 4.3 3.1 3.2 3.3 1.1 NS Interdental Overjet (mm) 0.9 2.0 0.0 2.0 0.9 NS Overbite (mm) 0.7 1.6 0.6 1.8 0.1 NS Interincisal angle () 2.1 12.0 1.5 7.0 3.6 NS Molar relationship (mm) 0.8 2.7 0.8 2.0 0.0 NS Maxillary dentoalveolar U1-Point A vert (mm) 1.1 2.2 1.2 1.6 0.1 NS U1 to FH () 1.2 7.1 0.5 4.6 0.7 NS Mandibular dentoalveolar L1-Point A Pg (mm) 1.9 2.6 0.4 1.4 1.5 NS L1-MPA () 4.5 6.8 0.4 3.8 4.1 NS NS, Not signiﬁcant; perp, perpendicular; Pg, pogonion; FH, Frankfort horizontal; PP, palatal plane; U1, maxillary central incisor; vert, vertical; L1, mandibular central incisor.

2.0 in the Q-H/C compared with the controls. This This result agrees with the outcome at the end of finding demonstrates that treatment with the Q-H/C active therapy with the same treatment protocol produces favorable skeletal control of the vertical reported in a previous short-term study.17 Similarly, in dimension in the short term. the short-term results of Pedrin et al,23 the treated group These findings were similar to those described in showed a significant closure of the anterior open bite of a previous short-term study that reported a significantly 5.0 mm, whereas Torres et al24 found an improvement in greater downward rotation (1.2) of the palatal plane overbite of 3.9 mm. In our study, a statistically signifi- associated with a significant reduction in the intermax- cant lingual tipping (3.7) of the mandibular incisors illary divergence (1.7) in the Q-H/C sample with to the mandibular plane contributed to the correction respect to the controls at the end of the active of overbite in the Q-H/C group. This treatment effect treatment.17 On the other hand, our short-term could be due to the normalization of function, such as treatment outcomes disagreed with those of Pedrin elimination of tongue thrusting and interruption of et al23 and Torres et al.24 The results of both studies sucking habits encouraged by the palatal crib.40 showed that the effects of therapy primarily were The statistical data can be accompanied by the anal- dentoalveolar without significant changes in the skeletal ysis of individual data: 24 of 28 subjects showed positive maxillary and mandibular components. The initial mean overbites at T2. Therefore, in this study, we assessed the amount of negative overbite (a measure of anterior clinical effectiveness for the treatment protocol in ap- dentoalveolar open bite) was 3.3 mm in the Q-H/C proximately 86% of patients with dentoalveolar open group. The average increase in overbite (4.2 mm) during bite at the end of active therapy. The failure of overbite Q-H/C therapy overcorrected the amount of anterior correction in the other 4 subjects was attributable to open bite at T2. This value was statistically significant their higher values for anterior open bite at T1. The when compared with the control group. prevalence rate for the success of Q-H/C therapy appears

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Table V. Comparison of long-term changes (T1-T3)

Q-H/C group (n 5 28) Control group (n 5 20)

Cephalometric measurement Mean SD Mean SD Difference Significance Maxillary skeletal SNA () 0.6 2.3 1.5 3.5 2.1 NS Point A-nasion perp (mm) 0.2 2.5 1.7 3.8 1.9 NS Mandibular skeletal SNB () 1.3 2.3 2.1 3.5 0.8 NS Pg-nasion perp (mm) 3.8 4.6 4.6 7.0 0.8 NS Co-Gn (mm) 14.2 6.1 15.8 4.4 1.6 NS Maxillary/mandibular ANB () 1.9 1.9 0.6 1.7 1.3 * Wits (mm) 0.6 3.6 2.3 3.7 1.7 NS Vertical skeletal FH-PP () 1.1 2.9 0.7 1.7 1.8 * MPA () 3.2 2.7 2.8 3.7 0.4 NS PP-mandibular plane () 4.3 3.0 2.1 3.3 2.2 * ANS-Me (mm) 6.3 3.3 7.7 3.1 1.4 NS Co-Go (mm) 7.1 5.1 8.5 3.9 1.4 NS Gonial angle () 6.0 4.2 4.5 3.6 1.5 NS Interdental Overjet (mm) 0.6 2.7 0.9 2.0 1.5 * Overbite (mm) 4.9 2.0 2.8 1.7 2.1 y Interincisal angle () 4.1 12.7 0.2 8.4 4.3 NS Molar relationship (mm) 1.3 2.6 0.8 2.1 0.5 NS Maxillary dentoalveolar U1-Point A vert (mm) 1.7 2.5 2.3 2.0 0.6 NS U1-FH () 1.0 8.4 0.7 6.3 1.7 NS Mandibular dentoalveolar L1-Point A Pg (mm) 1.0 2.3 0.9 1.8 0.1 NS L1-MPA () 0.8 6.1 2.4 4.9 1.6 NS NS, Not significant; perp, perpendicular; Pg, pogonion; FH, Frankfort horizontal; PP, palatal plane; U1, maxillary central incisor; vert, vertical; L1, mandibular central incisor. *P \0.05; yP \0.01. as a favorable result, and the prevalence is similar to the a significant improvement in maxillomandibular success rates reported in other studies on the early divergence of 2.2 in the Q-H/C group vs the control treatment of anterior open bite (80% according Torres subjects. This favorable outcome deserves to be et al23 and Pedrin et al24; 90% according Cozza emphasized because of its clinical impact on et al28). In our study, only 10 of the 20 subjects (50%) dentoskeletal open bite: it contributes to the overall of the control group showed spontaneous correction correction of anterior open bite significantly. of anterior open bite. Comparison between prevalence No previous clinical investigation has evaluated the rates of overbite correction at T2 was statistically effects of early correction of anterior open reevaluated significant, demonstrating the efficacy of treatment. at a 5-year follow-up with respect to a control sample In the posttreatment period (T2-T3), no significant with untreated anterior open bite. Only 1 study has changes in the Q-H/C subjects over the controls were addressed early correction with the Q-H/C appliance of found. Therefore, no relapse in overbite was noted after anterior open bite in mixed-dentition patients with an active treatment. adequate sample size and a control group.28 Evaluation The analysis of the overall results (Table V) showed of the results after 2 years of active treatment that intermaxillary sagittal skeletal relationships showed clinically significant improvements in both exhibited favorable changes compared with the control maxillomandibular vertical skeletal relationship (2.5) group, with a decrease in the ANB angle of 1.3.With and overbite (2.7 mm). respect to vertical skeletal features, the overall changes At a follow-up observation of 5 years, favorable reflected the T1 to T2 changes. The outcomes of changes in anterior dentoalveolar relationships were Q-H/C therapy produced a clinically significant found. An improvement in the sagittal skeletal downward rotation of the palatal plane of 1.8, with relationships (ANB, 1.3 in the Q-H/C vs the control)

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was associated with a significant reduction of 1.5 mm in bite in the mixed dentition. Am J Orthod Dentofacial Orthop 2005; overjet (1.5 mm in the Q-H/C vs the control). The Q-H/ 128:517-9. C group also showed a significant improvement in over- 7. Heimer MV, Tornisiello KCR, Rosenblatt A. Non-nutritive sucking habits, dental malocclusions, and facial morphology in Brazilian bite (2.1 mm) compared with the controls. The mean children: a longitudinal study. Eur J Orthod 2008;30:580-5. overbite increase in the Q-H/C group was 4.9 mm, pro- 8. Cozza P, Baccetti T, Franchi L, Mucedero M, Polimeni A. Trans- viding correction of the anterior open bite in 26 subjects, verse features of subjects with sucking habits and facial hyperdi- with a prevalence rate of 93%. This value was signifi- vergency in the mixed dentition. Am J Orthod Dentofacial cantly greater than that of the control group (70%), Orthop 2007;132:226-9. 9. Almeida RR, Ursi WJS. Anterior open bite: etiology and treatment. and it also was greater than that reported in the previous Oral Health 1990;80:27-31. study that assessed the clinical effectiveness for the same 10. English JD. Early treatment of skeletal open bite malocclusions. treatment protocol in approximately 85% of patients.28 Am J Orthod Dentofacial Orthop 2002;121:563-5. The 23% gain in therapeutic effect can be considered 11. Luzzi V, Guaragna M, Ierardo G, Saccucci M, Consoli G, Vestri AR, clinically significant, since it was achieved with a rela- et al. Malocclusions and non-nutritive sucking habits: a prelimi- nary study. Prog Orthod 2011;12:114-8. tively minimal burden on both the clinician and the pa- 12. Isçan HN, Akkaya S, Elçin K. The effect of spring-loaded posterior tient. The appliances used were noncompliance devices; bite block on the maxillo-facial morphology. Eur J Orthod 1992; during fixed appliance therapy, no auxiliaries (eg, verti- 14:54-60. cal or sagittal elastics) were applied. The results of this 13. Arat M, Iseri H. Orthodontic and orthopaedic approach in the study showed that in the long term the elimination of treatment of skeletal open bite. Eur J Orthod 1992;14:207-15. 14. Kuster R, Ingervall B. The effect of treatment of skeletal open bite oral habits permitted the normalization of function fa- with two types of bite-blocks. Eur J Orthod 1992;14:489-99. voring improved facial growth in both the sagittal and 15. Weinbach JR, Smith RJ. Cephalometric changes during treatment vertical planes. with the open bite bionator. Am J Orthod Dentofacial Orthop 1992;101:367-74. 16. Schulz SO, McNamara JA Jr, Baccetti T, Franchi L. Treatment CONCLUSIONS effects of bonded RME and vertical-pull chincup followed by fixed The treatment effects of the Q-H/C protocol in appliance in patients with increased vertical dimension. 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